// Copyright (c) 2021, gottingen group.
// All rights reserved.
// Created by liyinbin lijippy@163.com
//
// Character Map Class
//
// A fast, bit-vector map for 8-bit unsigned characters.
// This class is useful for non-character purposes as well.

#ifndef ABEL_STRINGS_INTERNAL_CHAR_MAP_H_
#define ABEL_STRINGS_INTERNAL_CHAR_MAP_H_

#include <cstddef>
#include <cstdint>
#include <cstring>
#include "abel/base/profile.h"

namespace abel {

namespace strings_internal {

class Charmap {
  public:
    constexpr Charmap() : m_() {}

    // Initializes with a given char*.  Note that NUL is not treated as
    // a terminator, but rather a char to be flicked.
    Charmap(const char *str, int len) : m_() {
        while (len--) SetChar(*str++);
    }

    // Initializes with a given char*.  NUL is treated as a terminator
    // and will not be in the charmap.
    explicit Charmap(const char *str) : m_() {
        while (*str) SetChar(*str++);
    }

    constexpr bool contains(unsigned char c) const {
        return (m_[c / 64] >> (c % 64)) & 0x1;
    }

    // Returns true if and only if a character exists in both maps.
    bool IntersectsWith(const Charmap &c) const {
        for (size_t i = 0; i < ABEL_ARRAY_SIZE(m_); ++i) {
            if ((m_[i] & c.m_[i]) != 0) return true;
        }
        return false;
    }

    bool IsZero() const {
        for (uint64_t c : m_) {
            if (c != 0) return false;
        }
        return true;
    }

    // Containing only a single specified char.
    static constexpr Charmap Char(char x) {
        return Charmap(CharMaskForWord(x, 0), CharMaskForWord(x, 1),
                       CharMaskForWord(x, 2), CharMaskForWord(x, 3));
    }

    // Containing all the chars in the C-std::string 's'.
    // Note that this is expensively recursive because of the C++11 constexpr
    // formulation. Use only in constexpr initializers.
    static constexpr Charmap FromString(const char *s) {
        return *s == 0 ? Charmap() : (Char(*s) | FromString(s + 1));
    }

    // Containing all the chars in the closed interval [lo,hi].
    static constexpr Charmap Range(char lo, char hi) {
        return Charmap(RangeForWord(lo, hi, 0), RangeForWord(lo, hi, 1),
                       RangeForWord(lo, hi, 2), RangeForWord(lo, hi, 3));
    }

    friend constexpr Charmap operator&(const Charmap &a, const Charmap &b) {
        return Charmap(a.m_[0] & b.m_[0], a.m_[1] & b.m_[1], a.m_[2] & b.m_[2],
                       a.m_[3] & b.m_[3]);
    }

    friend constexpr Charmap operator|(const Charmap &a, const Charmap &b) {
        return Charmap(a.m_[0] | b.m_[0], a.m_[1] | b.m_[1], a.m_[2] | b.m_[2],
                       a.m_[3] | b.m_[3]);
    }

    friend constexpr Charmap operator~(const Charmap &a) {
        return Charmap(~a.m_[0], ~a.m_[1], ~a.m_[2], ~a.m_[3]);
    }

  private:
    constexpr Charmap(uint64_t b0, uint64_t b1, uint64_t b2, uint64_t b3)
            : m_{b0, b1, b2, b3} {}

    static constexpr uint64_t RangeForWord(unsigned char lo, unsigned char hi,
                                           uint64_t word) {
        return OpenRangeFromZeroForWord(hi + 1, word) &
               ~OpenRangeFromZeroForWord(lo, word);
    }

    // All the chars in the specified word of the range [0, upper).
    static constexpr uint64_t OpenRangeFromZeroForWord(uint64_t upper,
                                                       uint64_t word) {
        return (upper <= 64 * word)
               ? 0
               : (upper >= 64 * (word + 1))
                 ? ~static_cast<uint64_t>(0)
                 : (~static_cast<uint64_t>(0) >> (64 - upper % 64));
    }

    static constexpr uint64_t CharMaskForWord(unsigned char x, uint64_t word) {
        return (x / 64 == word) ? (static_cast<uint64_t>(1) << (x % 64)) : 0;
    }

  private:
    void SetChar(unsigned char c) {
        m_[c / 64] |= static_cast<uint64_t>(1) << (c % 64);
    }

    uint64_t m_[4];
};

// Mirror the char-classifying predicates in <cctype>
constexpr Charmap UpperCharmap() { return Charmap::Range('A', 'Z'); }

constexpr Charmap LowerCharmap() { return Charmap::Range('a', 'z'); }

constexpr Charmap DigitCharmap() { return Charmap::Range('0', '9'); }

constexpr Charmap AlphaCharmap() { return LowerCharmap() | UpperCharmap(); }

constexpr Charmap AlnumCharmap() { return DigitCharmap() | AlphaCharmap(); }

constexpr Charmap XDigitCharmap() {
    return DigitCharmap() | Charmap::Range('A', 'F') | Charmap::Range('a', 'f');
}

constexpr Charmap PrintCharmap() { return Charmap::Range(0x20, 0x7e); }

constexpr Charmap SpaceCharmap() { return Charmap::FromString("\t\n\v\f\r "); }

constexpr Charmap CntrlCharmap() {
    return Charmap::Range(0, 0x7f) & ~PrintCharmap();
}

constexpr Charmap BlankCharmap() { return Charmap::FromString("\t "); }

constexpr Charmap GraphCharmap() { return PrintCharmap() & ~SpaceCharmap(); }

constexpr Charmap PunctCharmap() { return GraphCharmap() & ~AlnumCharmap(); }

}  // namespace strings_internal

}  // namespace abel

#endif  // ABEL_STRINGS_INTERNAL_CHAR_MAP_H_
